1. Field of the Invention
The present invention relates to a security device for preventing unauthorized use of a trailer of other vehicle, such as an RV, having a coupling pin to couple the trailer to a tractor or other vehicle.
2. Brief Description of the Related Art
Coupling devices for coupling a trailer to a tractor or other vehicle typically include a coupling pin attached to the front of the trailer and a complementary receptacle attached to the rear of the tractor or truck which releasably engages the trailer coupling pin while allowing relative pivoting of the trailer and the tractor. A coupling device in wide use today comprises a pin referred to as a king pin extending from the front of trailers and a complimentary skid plate receptacle or fifth wheel mounted to the rear of tractors. The king pin and skid plate are standardized so that any trailer having a king pin may be coupled to any tractor having a complementary skid plate.
Frequently, trailers are uncoupled from tractors, for example, during loading and unloading, for storing trailers when they are not being moved, or for using tractors independently of trailers, and left unattended. In such instances, an unauthorized person with a tractor having a complementary skid plate for the trailer king pin may simply couple to the trailer, connect the air hoses to release the trailer air brakes and haul the trailer away.
To prevent unauthorized use of trailers having a coupling pin, security devices are known which are secured to the trailer coupling pin so as to prevent coupling of the trailer coupling pin to a complementary receptacle on a tractor. Such security devices include a locking device by means of which the security device is locked to the trailer coupling pin. Security devices of that type are described in prior U.S. Pat. Nos. 4,697,444 and 4,553,415 to one of the inventors of the present invention. Although these devices performed satisfactorily in many circumstances, they could still be defeated through a variety of means, such as by drilling, by the application of heat, or by modifying a tractor skid plate to attached to the lock rather than to the trailer kingpin.
The present invention overcomes these shortcomings by significantly increasing the difficulty of defeating the lock by means of drilling, flame cutting, smashing, or modifying a skid plate to attach to a kingpin with a lock attached thereto.